Nature of Digital Radiography

Question 1

radiograph with no film, based on computer’s interpretation of how much radiation reached receptor

Answer 1

digital radiograph

Question 2

analog image (no numerical values), based on size/distribution of metallic silver particles

Answer 2

conventional film

Question 3

direct systems

Answer 3

CCD, CMOS, some flat panels

Question 4

in direct systems, image travels ______ from receptor to computer screen

Answer 4

immediately

Question 5

direct systems can have ___ sensors that are more ____ for patient

Answer 5

bulkier, uncomfortable

Question 6

indirect systems

Answer 6

photostimulable phosphor (PSP) sensors, some flat panels

Question 7

in indirect systems, images must be ___ from PSP sensor, so you do not ____ get image

Answer 7

scanned, immediately

Question 8

indirect sensors are ____/___ and can be more _____

Answer 8

thinner/flexible, comfortable

Question 9

image receptor name

Answer 9

film, detector, sensor

Question 10

flat panel detectors are used in _____ for things such as ________

Answer 10

extraoral radiograph, whole skull/CBCT

Question 11

array of pixels (picture elements) on a thin wafer of silicon

Answer 11

charged-coupled devices (CCD)

Question 12

______ ___ is an intensifying screen on a CCD that converts ____ photons to ____ photons

Answer 12

scintillating coating, x-ray, light

Question 13

light photons knock e- free in _____ silicon layer, leaving behind “electron holes” which are ______ charged

Answer 13

positive, positively

Question 14

e- holes are attracted to negative silicon layer, stored as a ___ ___

Answer 14

charge packet

Question 15

charge packets are read-out by sensor electronics row-by-row in a _____ ____

Answer 15

bucket brigade

Question 16

______ convert charge signals to digital (numerical) info

Answer 16

ADC analog-to-digital converter

Question 17

CMOS stands for

Answer 17

complimentary metal oxide semiconductor

Question 18

simpler circuit design where there is no bucket brigade but rather each pixel has its own read-out device

Answer 18

CMOS

Question 19

PSP composed of…

Answer 19

europium-activated barium fluorohalide

Question 20

read-out of PSP: trapped e- return to ___ energy state and ___ ____ which is then turned to digital info

Answer 20

lower, emit light

Question 21

PSP stores a portion of energy as e- trapped in ____ energy states

Answer 21

higher

Question 22

PSP needs to be “_____” with bright light before using

Answer 22

“erased”

Question 23

PSP should be processed _____

Answer 23

ASAP

Question 24

things that can degrade a PSP image

Answer 24

• waiting to process
• heat (releases light the same way a light does)
• bright light in room

Question 25

in digital radiography, each pixel signal intensity is stored as a _____

Answer 25

number

Question 26

the higher the bit depth, the ___ shades of grey

Answer 26

more

Question 27

our eyes can only detect ______ shades of grey depending on viewing conditions

Answer 27

20-50

Question 28

ability to see difference between different greyscale values

Answer 28

contrast resolution

Question 29

capacity for distinguishing fine detail which is limited by ____ ____

Answer 29

spatial resolution, pixel size

Question 30

spatial resolution is measured in ______

Answer 30

line pairs

Question 31

the higher the line pair, the ___ the resolution

Answer 31

higher

Question 32

line pairs intraoral film = digital images = eyes =

Answer 32

- greater than 20 line pair/mm - 7-10 line pairs/mm - 4-6 line pairs/mm

Question 33

____ can overcome the resolution limit of our eyes

Answer 33

magnification

Question 34

ability to respond to small amounts of radiation

Answer 34

detector sensitivity

Question 35

detector sensitivity impacted by...

Answer 35

- detector efficiency - pixel size - system noise

Question 36

increased sensitivity means you need _______ to get an image

Answer 36

less exposure/dose

Question 37

detector sensitivity classifiers for intraoral, extraoral, digital

Answer 37

``` intraoral = by speed (D, E, F, etc.) extraoral = screen/film combo digital = no agreed upon classifier ```

Question 38

ability to capture a range of x-ray exposures/dose and still procedure acceptable image

Answer 38

detector latitude

Question 39

detector latitude: CCD and CMOS have a ____ range PSP have a ____ range

Answer 39

narrow, wider

Question 40

a detector with a high sensitivity (does/does not) necessarily have high latitude

Answer 40

does not

Question 41

glassy/glossy/reflective screen monitors can be ______ in ________

Answer 41

problematic, bright viewing environments

Question 42

limited viewing ____ can be ___ for interpretation on monitors

Answer 42

angles, problematic

Question 43

the change in stimulus that will be just noticeable is a constant ratio of the original stimulus

Answer 43

weber's law

Question 44

term for reducing file size while preserving 100% of data

Answer 44

lossless

Question 45

term for reducing file size while losing data

Answer 45

lossy

Question 46

international standard language for electronic communication of digital image

Answer 46

DICOM

Question 47

DICOM stands for...

Answer 47

digital imaging and communications in medicine standard

Question 48

image enhancements

Answer 48

- brightness/contrasts - sharpening - color - magnification - filters to modify noise

Question 49

digital radiography advantages

Answer 49

-instant images -consistent quality -high signal:noise ratio -image manipulation -lower radiation dose -easy to store and transfer